Fluid driven motor



y 1941? w. BOND 2,240,686

' FLUID DRIVEN MOTOR I Original Filed Dec. 15, 1937 2 Sheets-Shegt l (I 7/ FIG. 9

w. L. BOND 2,240,686

FLUID DRIVEN Mb'roR Original Filed Dec. 15, 1937 2 Sheets-Shee t 2 Z: v a7 lNl/EN 7'09 W L. BOND A T TORNEV Patented May 6, 1941 FLUID DRIVEN MOTOR Walter L. Bond, South Orange, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Original application December 15, 1937, Serial No.

1940, Serial No. 331,285

4 filaims.

This invention relates to a fluid driven motor and particularly to a fluid driven motor adapted to be operated at high speeds with substantially no vibration.

An object of the invention is to increase the efficiency of fluid driven motors.

Another object of the invention is the reduction of vibration of fluid driven motors when operated at high speeds.

This application is a division of my application Serial No. 179,959, filed December 15, 1937, Cutting tool.

In the preparation of Rochelle salt plates, which have been commonly used for some time as piezoelectric elements in such electrical circuits as oscillators and wave filters and which have more recently been proposed for use in relays as disclosed for example in W. P. Mason Patent 2,166,763, issued July 18, 1939, Piezoelectric apparatus and circuits, it is the usual practice to cut a number of relatively thin, substantially flat, plates or slabs from a larger crystal. As a rule these slabs, even when out by means of the accurate and precise apparatus now available in modern shops, are not of the required thinness and in many cases the major surfaces do not present the high degree of plane parallelism required to give the plate the accurate characteristics demanded of it. It is generally necessary therefore to surface or grind down the plates in some manner after they have been cut from the larger crystal.

Various methods of thinning down the R- chelle salt plates have been tried, none of which, in the experience of applicants assignees, has proven entirely satisfactory. For example, the type of grinding plate commonly referred to as a lap has been used to a considerable extent with fair results. However, this is a relatively slow process and frequent breakage results. Edged tools such as the common lathe and the planer have also been used but breakage has been excessive due to the fragility of the thin Rochelle salt plate. In the instance of use of the lathe breakage results from the stresses set up in the plate due to centrifugal force resulting from rotation thereof while in the instance of the planer the stresses set up in the plate when it is forcibly moved against the stationary cutting tool, are such that they cannot be withstood by the fragile plate.

Use of the surfacing tool of the type disclosed in my copending application referred to above, however, involves none of the difliculties of previous methods and results in a rapid and efli Divided and this application Apr l 24,

cient surfacing action. Here the plate remains substantially stationary so that all possible stresses due to motional effects are avoided, the only movement of the plate being that involved in slowly feeding it forward to bring the entire surface progressively into contact with the rapidly rotating cutting member. Factors believed to play a major part in the successful operation of the device are, first, the provision of a nicely balanced cutter and, second, the provision of a fluid driven motor of the type contemplated by the present invention for rotating the cutter at a high rate of speed, of the order of 20,000 revolutions per minute. The precise balance of the cutter results from features incorporated in the driving motor, and from use of a specially shaped cutter arm and the use of a single compact cutting point capable of being balanced to an extent that would be difficult to achieve if a cutting element with a longer edge were used. Rotation of the cutter by the fluid driven motor at the high rate of speed referred to results from the use of compressed air as a driving force.

Operation of the cutting arm at a relatively high rate of speed results in a rapid surfacing action, at the same time permitting an arrangement whereby only a minute portion of the material is removed by each rotation of the cutter. In view of this fact and the added fact that the cutter is adjusted to work on the uncut shoulder of the plate alone, substantially no stress is set up in the finished portion of the plate. The plate itself is not rotated so that stress due to centrifugal force is not set up in the material.

For certain applications of the Rochelle salt plates, particularly when used in electric relays of the type disclosed in the Mason patent referred to above, it is desirable to leave a shoulder on the end of the thin plate.

In accordance with a feature of the invention described in the copending application referred to above, special feeding mechanism is provided whereby a predetermined portion of the plate is left unground or is ground only slightly as compared to the rest of the plate, this predetermined portion being left as a mounting lug or shoulder for the plate.

In accordance with a feature of the present invention a particularly compact, easily assembled, inexpensive and efficient rotor assembly is provided.

Full understanding of the operation of the invention and of the various .valuable features thereof may be gained from consideration of the following detailed description together with the annexed drawings in which:

Fig. 1 is a view in perspective of a machine for susfacing Rochelle salt plates of the type described in the copending application referred to above;

Fig. 2 is an enlarged sectional view of a portion of the machine showing particularly the rotor assembly;

Fig. 3 is a plan view of the machine with the work-table and rotor assembly removed showing particularly the cam arrangement for shifting the position of the Work-table;

Fig. 4 is a sectional view taken on lines 4-4 of Fig. 3, the work-table being shown in place;

Fig. 5 is a view of the cutter arm shown in inverted position in order to disclose the cutting point more clearly; and

Fig. 6 is a view in perspective of a Rochelle salt plate after having been surfaced by the machine illustrated.

Referring now to Fig. 1, the surfacing machine comprises a reciprocating platform II supported on base 42. Work-table I3 is supported by and moves with platform II. Rotor block I4 is supported by block I I, which, in turn, is mounted on plate I8, the latter being movable vertically on upright I9 of base I2.

Platform II may be moved forward or backward by rotation of crank 2I which is supported on extension 22 of base I2, this movement resulting from a driving connection between screw 23 (rotated by crank 2|) and shoulder 24 (Fig. 4) carried by platform II. Accordion pleated fibre guard 26 serves to protect the screw mechanism from dust.

Snindle 21, which is rotatably supported on p etiorm I terminates at one end in cam finger and at t e other end in shoulder 42 (Fig. 3). Shoulder 42 is positioned in recess 43 (Fig. 4) provided in. post 44 carried by work-table I3. One-end of flat spring 40, which is attached to pla e 4? by screw 5!, is positioned in recess 43 also. the tension of spring 45 acting to normally hold work-table I3 in its raised position. The biasing force of spring 46 is increased by engagement of the spring with lug 52 (Fig. 4) of plate 41. As platform II is moved forward. the tip of cam finger M is, as shown in Fig. 1, brought into en agement with cam block 53 which is mounted on base I2, and. as the forward movement of piatform II continues, spindle 21 is rotated in a co1.inter-clockwise direction due to the (ramming action of block 53 on finger 4I. In view of the engagement of shoulder 42 (Fig. 3) with the walls of recess 43, this rotation of spinrile 2"! results in work-table I3 being forced down to its lower position against the biasing action of ing 46. The purpose of this shift in the position of the work-table will be apparent from subsequent description of the operation of the machine.

The vertical position of the rotor assembly may be changed by rotation of crank arm (I which, in turn, (25.13125 rotation of screw I2 and vertical movement of plate I8.

The rotor assembiy consists of an air driven turbine plate i3 provided with a series of air receiving pockets, as 18 and 19, on the lower peripheral edge. This turbine plate is rotatably supported on rotor block l4 being held in position on sh'aft 14 by nut 1-6 (Fig. 2). Plate 13 is mechanically joined to shaft 14 so that rotation of the plate causes rotation of the shaft and of cutter arm 11 which is attached to the lower end of the shaft.

Ring BI is positioned in contact with lip 82 of rotor block I4 and serves as a closure for passageway 83 provided in the lower surface of lip 82 thereby forming a substantially closed circumferential air chamber (Fig. 2). Air is admitted under high pressure to this chamber from supply pipe 84 and is directed against the edges of the air pockets in rotor plate I3 by a series of ducts, as 86 and 81, provided in lip 82. These ducts are drilled at a predetermined angle whereby the air jets strike the edges of the pockets at the exact points necessary for the most efficient application of power. In order to prevent vibration, shaft I4 is supported by rotor bearings I04 and I02.

Cutter arm TI is attached to the lower end of shaft 14 by suitable means, for example, by a threaded connection. Cutting point III which is carried by arm 'I'. (Fig. 5) may comprise a diamond particle affixed in position on the arm by any suitable method. For example, the point may be held in place by an electro-deposited. metal coating in accordance with the teachings of Broughton Patent 2,073,678 issued March 16, 1937. The cutter arm is carefully designed in order to assure exact balance. both static and dynamic. of the rotor assembly.

It will be apparent from the above that the rotor assembly provided is particularly compact and inexpensive and yet capable of unusually efficient operation. The unit is simple to assemble while obtaining the necessary static and dynamic balance of the rotating members is greatly facilitated due to the small number of moving parts involved.

A guide H2 is positioned on rotor block I4 and acts to protect the operator of the device from flying particles.

A hard rubber support H3 is carried by worktable I3, grooves which assist in retaining the work in place being provided in the support. The hard rubber base acts to prevent a rapid transfer of heat from the work to metal table I3 thereby playing a valuable part in preventing breakage of the work.

In order to further describe the machine let us assume that it be desired to thin down Rochelle salt plate I IS in order to produce a plate of the nature used in piezoelectric relays, such a plate being shown in Fig. 6. As shown in Fig. 6, an enlarged portion or shoulder I20 is left on the end of the plate for mounting purposes.

At the start of the process the rotor assembly is raised slightly by rotation of crank 'II and the work-table assembly is brought to its starting position by rotation of crank 2I. The Rochelle salt plate II8 which is to be surfaced is then mounted in position on work support II3 being held in place thereon by suitable means, for example by the use of an adhesive. Blocks such as I2I and I22 may be inserted in certain of the grooves provided in support I in order to prevent fiow of the adhesive and possible consequent movement of plate II8. The rotor assembly is then lowered by rotation of crank II until cutting point III is at the proper level to contact the surface of plate I I8 when rotated. Pressure control valve I3I is now opened admitting air under pressure into chamber 83 which results in rotation of shaft 14, and cutter arm I1 carried thereby, at a high rate of speed of the order of 20,000 revolutions per minute.

The work-table assembly is now fed forward by rotation of crank 2| so that the entire surface of plate H8 from end to end is progressively brought into contact with rapidly rotating cutting point Hi. In view of the rapid rate at which the cutting point is rotated, the work may be fed forward fairly rapidly without resulting in removal of more than a minute portion of the surface by each rotation of the cutting point. While it has been found necessary, in order to prevent fracture of the fragile plate, to remove only a minute portion of the previously uncut surface of the plate by each rotation of the cutter it is, at the same time, desirable from the standpoint of economical production that a fairly rapid feeding action be utilized.

In view of the careful design of, and the supporting arrangement provided for the entire rotor assembly, substantially no vibration of the cutting tool occurs even though it is driven at the high rate of speed necessary for the successful operation of the tool. No small part in the elimination of vibration is played by the design of the cutting element itself and the cutter arm which carries it; the cutter arm is specially shaped'to achieve static and dynamic balance of the assembly while the use of the single short cutting point, instead of a longer blade, facilitates balancing the unit.

As platform II is fed forward to the position illustrated in Fig. 1, the tip of cam finger 4| engages the cam edge of block 53 and as forward movement of the platform continues, spindle 21 is rotated and causes work-table I3 to be lowered slightly in the manner described above. This means, of course, that plate H8 is moved away from cutting point Ill so that the remaining surface of the plate is not ground, or is ground only slightly, the result being that a relatively thick shoulder (corresponding to shoulder I20 of Fig. 6) remains on the end of plate H8. As explained above, this shoulder serves as a means for mounting the plate.

Upon completion of the cut the plate, if of the required thinness, is removed from work support H3. If further Working is desirable, platform H is returned to starting position by rotation of crank 2|, the position of the cutter as sembly is properly adjusted and the thinning process described above is repeated.

While a specific embodiment of the invention has been selected for detailed description, the invention is not, of course, so limited in its application. The embodiment described should be taken as illustrative of the invention and not as restrictive thereof.

What is claimed is:

1. In a fluid operated tool, a cylindrical rotor supporting block, said block being of greater circumference at one endthan at the other end, a peripheral lip on said block near the larger end thereof, said lip having a peripheral groove therein, a ring positioned on said block adjacent to said lip and acting in conjunction with said groove in said lip to form a substantially closed fluid chamber, a shaft rotatably mounted in said rotor supporting block, a rotor plate attached to one end of said shaft, said rotor plate being rotatably supported on the larger end of said block, said rotor plate having a series of pockets therein at its peripheral edge and means for admitting fluid under pressure to said chamber, said lip having means therein for directing fluid from said chamber against the edges of said pockets to cause rotation of said rotor plate.

2. In a fluid operated tool, a cylindrical rotor supporting block, said block being of greater circumference at one end than at the other end, a peripheral lip on said block near the larger end thereof, said lip having a peripheral groove therein, a ring positioned on said block adjacent to said lip and acting in conjunction with said groove in said lip to form a substantially closed fluid chamber, a shaft rotatably mounted in said rotor supporting block, a rotor plate attached to one end of said shaft, said rotor plate being rotatably supported on the larger end of said block, said rotor plate having a series of pockets therein at its peripheral edge, and means for admitting fluid under pressure to said chamber, said lip having a plurality of radial ducts therein for directing fluid from said chamber against the edges of said pockets to cause rotation of said rotor plate.

3. In a fluid operated tool, a cylindrical rotor supporting block, said block being of greater circumference at one end than at the other end, a peripheral lip on said block near the larger end thereof, said lip having a peripheral groove therein, a ring positioned on said block adjacent to said lip and acting in conjunction with said groove in said lip to form a substantially closed fluid chamber, a shaft rotatably mounted in said rotor supporting block, a rotor plate attached to one end of said shaft, said rotor plate being rotatably supported on the larger end of said block, said rotor plate having a series of pockets therein at its peripheral edge, and means for admitting fluid under pressure to said chamber, said lip having means therein for directing fluid from said chamber against the edges of said pockets to cause rotation of said rotor plate and shaft.

4. In a fluid operated tool, a rotatable shaft, means for supporting said shaft comprising a cylindrical supporting block of greater circumference at one end than at the other, means for rotating said shaft including a rotor plate attached to one end of said shaft, said rotor plate being rotatably supported on the larger end of said block, a peripheral lip on said block near the larger end thereof, said lip having a. peripheral groove therein, means acting in conjunction with said groove to form a substantially closed fluid chamber, said rotor plate having a series of pockets therein at its peripheral edge, and means for admitting fluid under pressure to said chamber, said lip having means therein for directing fluid from said chamber against the edges of said pockets to cause rotation of said rotor plate and said shaft.

WALTER L. BOND. 

